Activities For Ethylene Oligomerization Research Articles

Ethylene oligomerization over mesoporous FeNi-BTC catalysts: Effect of the textural properties of the catalyst on the reaction performance

Mesoporous FeNi-1,3,5-benzenetricarboxylates (FeNi-BTCs) with different Fe/Ni ratios were prepared, and their catalytic activities in ethylene oligomerization were evaluated. The textural properties of the bimetallic FeNi-BTC were considerably affected by the Fe/Ni ratio, exhibiting a volcano relationship, with the maximum specific surface area, pore volume, and diameter observed at Fe/Ni = 10/90. The enhanced textural properties of the FeNi-BTC catalyst resulted in accelerated ethylene oligomerization and an increased C6–C8 oligomer selectivity. Using the Fe10Ni90-BTC catalyst, the rate of ethylene consumption and C6–C8 oligomer selectivity reached as high as 2823 g C2H4/g Ni h and 49%, which were approximately four- and two-fold higher than those of Ni-BTC, respectively. The remarkable reaction performance of the Fe10Ni90-BTC catalyst could be rationalized in terms of its well-defined mesoporous structure, which could decrease the mass transfer resistance and thereby facilitate intrapore ethylene diffusion during ethylene oligomerization. These results clearly demonstrate the potential of the FeNi-BTC catalyst in promoting ethylene oligomerization with a high activity and selectivity towards C6∼C8 oligomers. In the catalyst recycling study, whereas the catalytic activity decreased due to the partial deformation of the FeNi-BTC catalyst with repeated recycling, the selectivity towards C6+ oligomers gradually increased.

Ethylene (co) oligomerization using iminopyridyl Ni(II) and Pd(II) complexes bearing benzocycloalkyl moieties to access hyperbranched ethylene oligomers and ethylene-MA co-oligomers.

Hyperbranched ethylene oligomers and polar functionalized co-oligomers synthesized via ethylene chain walking (co) oligomerization is a very attractive strategy. In this study, a series of dibenzhydryl iminopyridyl ligands with benzocycloalkyl and naphthyl moieties and the corresponding Ni(II) and Pd(II) complexes were synthesized and characterized. The Ni(II) complexes were highly effective in ethylene oligomerization and ethylene oligomers with hyperbranched microstructures were generated from this system. The corresponding Pd(II) complexes showed moderate oligomerization activities in ethylene oligomerization and hyperbranched ethylene oligomers were also yielded from the system. More significantly, the Pd(II) complexes can also effectively promote the co-oligomerization of ethylene with methyl acrylate (MA) to obtain hyperbranched polar functionalized ethylene-MA co-oligomers. The reaction temperature, catalyst ligand structure and metal type all have significant effects on ethylene (co) oligomerization with respect to catalytic activity, molecular weight and topology of the oligomers.

Preparation of NiO /SiO2–Al2O3 catalysts by a homogenous precipitation method and their catalytic activity for ethylene oligomerization

NiOx/SiO2–Al2O3 catalysts with different pore structures (BET specific surface area: 303–709 m2 g−1, average pore size: 2.2–5.1 nm), acid properties (total amount of acid sites: 0.99–1.66 mmol g−1), and NiO particle sizes (4.6–14.7 nm) were prepared, and the structural factors influencing their catalytic activity for ethylene oligomerization were studied. SiO2–Al2O3 support was prepared by means of a homogeneous precipitation method, and supports with different physicochemical properties were obtained by changing the preparation conditions. Ni was loaded by means of an impregnation method. Catalytic reactions were performed in a fixed-bed down-flow reactor operated at 300 °C and 0.1 MPa. NiOx/SiO2–Al2O3 catalysts prepared with the homogenous precipitation method had a higher surface area, more uniform pore size, and a larger amount of acid sites, and they showed a higher activity not only compared with NiOx/SiO2–Al2O3 catalysts prepared by means of our previous coprecipitation method but also compared with Ni-AlSBA-15, the best heterogenous catalyst for ethylene oligomerization reported to data. The catalytic activities of the NiOx/SiO2–Al2O3 catalysts strongly depended on the BET specific surface area and the amounts of acid sites. The optimal amounts of weak, medium-strength, strong, and total acid sites were 0.5, 0.3, 0.4, and 1.2 mmol g−1, respectively. Examination of the structure–activity relationships of the catalysts suggested that their catalytic activity was promoted by close contact between the Ni and acid sites.

Polynuclear (α‐diimine) nickel(II) complex as catalyst for ethylene oligomerization

AbstractLate transition metal catalysts with single or multiple active centers have great attention in the ethylene oligomerization application owing to their unique properties. A new polynuclear (α‐diimine) nickel(II) complex (PS‐Ni complex) bearing the conjugated poly(Schiff‐base) ligand (PS‐ligand) was synthesized. The structures and the composition of the PS‐ligand and the PS‐Ni complex were characterized by Fourier transform infrared (FTIR) analysis, X‐ray diffraction (XRD), X‐ray photoelectron spectroscopy (XPS), scanning electron microscopy (SEM), thermogravimetric (TG) analysis, nuclear magnetic resonance (NMR) and gel permeation chromatography (GPC). The PS‐Ni complex was used as precatalyst in ethylene oligomerization combined with methylaluminoxane (MAO) and has good catalytic activity for ethylene oligomerization under mild conditions. Compared with the corresponding mononuclear (α‐diimine) nickel(II) complex, the PS‐Ni complex showed higher activity of 17.62 × 105 g/(mol Ni•h), and the main products were C4 and C6 olefins in cyclohexane when the dosage of precatalyst was 2 μmol, the Al/Ni molar ratio was 500, the ethylene pressure was 0.5 MPa, the reaction time was 60 min, and the reaction temperature was 25°C. The main oligomers were α‐olefins, and the selectivity was up to 98.68%, due to the more electron‐deficient catalytic centers of the conjugated structure of poly(Schiff‐base) ligand.

Identification of the structure of Ni active sites for ethylene oligomerization on an amorphous silica-alumina supported nickel catalyst

The structure of Ni active sites supported on amorphous silica-alumina supports with different contents of Al2O3 loadings in relation to their activities in ethylene oligomerization were investigated. Two kinds of Ni sites were detected by in situ FTIR-CO and H2-TPR experiments, that are Ni2+ cations as grafted on weak acidic silanols and Ni2+ cations at ion-exchange positions. The ethylene oligomerization activities of these Ni/ASA catalysts were found an ascending tendency as the Al2O3 loading decreased, which could be attributed to the enriched concentration of Ni2+ species on acidic silanols with a weaker interaction with the amorphous silica-alumina support. These Ni2+ species were more easily to be evolved into Ni+ species, which has been identified to be the active sites of ethylene oligomerization. Thus, it seems reasonable to conclude that Ni2+ species grafted on acidic silanols were the precursors of active sites.

Ethylene oligomerization reactions catalyzed by recyclable Fe(II), Ni(II) and Co(II) complexes immobilized on Fe3O4 magnetic nanoparticles

• Fe 3 O 4 MNPs immobilized metal complexes synthesized and characterized • Activation with EtAlCl 2 afford active ethylene oligomerization catalysts • Butene and hexene oligomers major products in heptane • Immobilized complexes effectively recycled via magnetic separation • Recycled catalysts maintained both catalytic activity and selectivity. Reactions of Fe 3 O 4 magnetic nanoparticles supported ligands, phenol((triethoxysilyl)propylimino)ethyl ( L1@Fe 3 O 4 ) and phenol((triethoxysilyl)propylimino)methyl ( L2@Fe 3 O 4 ) with appropriate metal salts afforded the respective immobilized complexes Ni1@Fe 3 O 4 , Ni2@Fe 3 O 4 , Co1@Fe 3 O 4 , Co2@Fe 3 O 4 , Fe1@Fe 3 O 4 and Fe2@Fe 3 O 4 . The complexes were characterized using FT-IR spectroscopy, thermogravimetric analyses (TGA), transmission electron microscopy (TEM), scanning electron microscopy (SEM), powder X-ray diffraction (PXRD), energy dispersive X-ray (EDX), inductively coupled plasma optical emission spectroscopy (ICP-OES) and vibrational sample magnetometry (VSM). Activation of the complexes with EtAlCl 2 afforded active catalysts for ethylene oligomerization to a tune of 97 600 g mol −1 h −1 under optimized conditions. Both ethylene oligomers and alkylated products were obtained depending on the solvent medium. The identity of the ligand and metal atom influenced the catalytic performance of the complexes. The immobilized complexes were recycled via magnetic separation in five successive runs without significant loss of catalytic activity and selectivity.

Star iminopyridyl iron, cobalt and nickel complexes: synthesis, molecular structures, and evaluation as ethylene oligomerization catalysts

A novel star iminopyridyl ligand was synthesized in modest yield with 1.0 G star macromolecule and pyridine-2-carboxaldehyde as the raw materials. Reactions of the star iminopyridyl ligand with Fe(II), Co(II) and Ni(II) salts afforded metal complexes (Cat-Fe, Cat-Co and Cat-Ni) in good yields. The compounds were characterized by FT-IR, 1H NMR, 13C NMR, UV–Vis, ESI–MS and ICP-MS. In the presence of methylalumoxane (MAO), the iron, cobalt and nickel complexes have demonstrated higher ethylene oligomerization activity (up to 4.28 × 105 g/(mol Co h)), affording C4 as the major product as well as C6, C8 and C10-18 oligomers. The catalytic activity was quite sensitive to the kind of species. The nature of solvent and co-catalyst significantly affected both the catalytic activity and product distribution. Moreover, the effect of oligomerization parameters (reaction temperature, [Al]/[Co] molar ratio, ethylene pressure) on the catalytic activity and the product distribution was investigated.

Ethylene oligomerization with 2-hydroxymethyl-5,6,7-trihydroquinolinyl-8-ylideneamine-Ni(II) chlorides

A series of Ni complexes of the general formula [2-(MeOH)-8-{N(Ar)}C9H8N]NiCl2, where Ar = 2,6-Me2C6H3 in Ni1; 2,6-Et2C6H3 in Ni2; 2,6-i-Pr2C6H3 in Ni3; 2,4,6-Me3C6H2 in Ni4; 2,6-Et2-4-MeC6H2 in Ni5 and 2,4,6-t-Bu3C6H2 in Ni6 has been synthesized and characterized by elemental analysis and IR spectroscopy. On activation with MMAO or Et2AlCl, these complexes showed high activity in ethylene oligomerization, reaching 2.23 × 106 g·mol–1 (Ni) h–1 at 30 °C with the Al/Ni ratio of 5500 and 9.11 × 105 g·mol–1 (Ni) h–1 with the Al/Ni of 800, respectively. Moreover, the content of α-C4 indicated high selectivity exceeding 99% in the Ni/Et2AlCl system. Comparing with the previous report by our group, this work discloses higher activity, presumably due to the substituent at the 2-position within the ligand influencing the steric hindrance around the metal atom. Furthermore, it is worth noting that the branched alkenes have been observed (iso-C6: 35.3 – 57.2%) in the oligomerization products.

Chromium(III) complexes based on phenoxy-imine ligands with pendant N- and O-donor groups as precatalysts for ethylene oligomerization: synthesis, characterization, and DFT studies

Chromium complexes of general formula [Cr{ZNO}(THF)Cl2] [2a, ZNO = C9H6N-8-(N=CH)-2,4-tert-butyl-2-(OC6H2); 2b, ZNO = Ph(NH)-C2H4-(N=CH)-2,4-tert-butyl-2-(OC6H2); 2c, ZNO = 2-MeO-Ph-CH2-(N=CH)-2,4-tert-butyl-2-(OC6H2); 2d, ZNO = 2-PhO-Ph-(N=CH)-2,4-tert-butyl-2-(OC6H2); 2e, ZNO = PhO-C2H4-(N=CH)-2,4-tert-butyl-2-(OC6H2)] and the bis(ligand) complex [Cr{C9H6N-8-NH2}2Cl2]Cl (4) were synthetized and characterized by elemental analysis, IR spectroscopy, and by X-ray crystallography for 4. In the solid state, 4 is monomeric with two 8-amino-quinoline acting as bidentate ligands and two chloride ligands in cis position. The DFT calculations showed slightly higher HOMO energy for 2d. In addition, the energy levels of the LUMO are slightly influenced by pendant O- and N-donor group. Particularly, the LUMOs for complexes 2a and 2d show a small contribution from Cr and Cl atoms as compared to other chromium complexes (2b, 2c and 2e), and the orbitals are almost entirely delocalized over the phenoxy-imine unit. Upon activation with methylaluminoxane (MAO), chromium precatalysts 2a-2e showed good activity in ethylene oligomerization (TOF = 22.0 – 52.7 × 103 (mol ethylene)(mol Cr)−1⋅h−1 at 80°C) with Schultz-Flory distribution of oligomers (KC4-C10 ≈ 0.92), and production of polymer varying from 2.9 to 22.3 wt.%. The catalytic performance is mainly controlled by electronic effects at the phenoxy-imine ligands. The bis(ligand) chromium complex 4 showed good activity in ethylene oligomerization (TOF = 39,400 (mol ethylene)(mol Cr)−1 h−1), producing mostly oligomers (95.2 wt% of total products) with high selectivity for α-olefins. The highest activity among the six precatalysts screened was reached with 2c (TOF = 52,700 mol(ethylene)•mol(Cr)−1•h−1).

Effect of an additional donor on decene formation in ethylene oligomerization catalyzed by a Cr/PCCP system: a combined experimental and DFT study

Cr catalyst based on a PCCP ligand shows high activity in ethylene oligomerization, giving 1-hexene and considerable C10 fraction. DFT calculation results are consistent with the experimental observations on the distribution of C10 isomers.

New chromium(III)-based catalysts for ethylene oligomerization

The report focuses on the new precatalysts for ethylene oligomerization. The five chromium(III) complex compounds containing the following ligands: dipicolinate anion, oxalate anion, 5-aminopyridine-2-carboxylate anion, 2,2′-bipyridine and 4,4′-dimethoxy-2,2′-bipyridine have been examined towards catalytic activity for ethylene oligomerization. The chromium(III) complexes have been activated by modified methylaluminoxane. The obtained oligomers have been investigated by MALDI-TOF–MS, thermal analysis and infrared spectroscopy. The results revealed that the examined chromium(III) complexes are highly active catalysts for ethylene oligomerization. The values of catalytic activities of the examined complexes are in the range 1860 – 3798 g∙mmol-1∙h-1∙bar-1.

Chromium Complexes Supported by Phenyl Ether‐Pyrazolyl [N,O] Ligands as Catalysts for the Oligo‐ and Polymerization of Ethylene

A new series of Cr (III) complexes [Cr{1‐(3‐phenoxypropyl)‐1H‐pyrazole}Cl3]2 (Cr1), [Cr{1‐(3‐phenoxypropyl)‐3,5‐dimethyl‐1H‐pyrazole}Cl3]2 (Cr2), and [Cr{1‐(3‐phenoxypropyl)‐3‐phenyl‐1H‐pyrazole}Cl3]2 (Cr3) have been synthesized and characterized by elemental analysis, high‐resolution mass spectrometry (HRMS) and IR spectroscopy. Upon activation with methylaluminoxane (MAO), chromium precatalysts Cr2 and Cr3 showed moderate activity in ethylene oligomerization [TOF = 17,900–29,200 mol (ethylene)·mol (Cr)−1·h−1 at 80 °C] with Schultz‐Flory distribution of oligomers (K = 0.54–0.66) and production of polymer varying from 2.8 to 6.7 wt.%. On the other hand, under identical oligomerization conditions, Cr1/MAO behaved as a polymerization catalyst generating predominantly polyethylene (63.7 wt%). The amount of 1‐butene is the largest component in the liquid fraction suggesting that these precatalysts operate via a Cossee‐Arlman mechanism. The catalytic activities, selectivity and product distribution are quite sensitive to the R‐group at the 3‐ and 5‐position of the pyrazolyl ring. Based on the electronic and steric effects of R‐ substituents, it is possible to stablish a trend of activity: Cr2(PzMe2) > Cr3(PzPh) > Cr1(Pz). Moreover, the effect of oligomerization parameters (cocatalyst, temperature, [Al]/[Cr] molar ratio, time) on the activity and on the product distribution were examined.

Unsymmetrical pyrazole-based PCN pincer NiII halides: Reactivity and catalytic activity in ethylene oligomerization

The reactivity of unsymmetrical pyrazole-based PCN pincer Ni(II) halides has been tested in the presence of copper(II) halides as an oxidizing agent as well as with NaBH4 and LiAlH4 as a hydride source. While the reaction with CuX2 resulted into the generation of metastable PCN pincer Ni(III) species, the treatment of (tBuPCN)NiCl with NaBH4 led to the preparation and isolation of the borohydride complex (tBuPCN)Ni(BH4). Attempts to isolate nickel-hydride species upon treatment of (tBuPCN)NiCl with either NaBH4 or LiAlH4 invariably led to the formation of free PCN(H) ligand and metallic Ni(0) nanoparticles after an in situ reductive elimination from the (metastable) hydride derivative (tBuPCN)NiH. Finally, the halide complexes (pre-activated by MMAO) have been tested as homogeneous catalysts in ethylene oligomerization showing moderate activity (∼ 14 × 103 molC2H4⋅molNi−1⋅h−1) with the formation of even-numbered olefins (mainly C4–C10 fractions) as products.

Nickel complexes based on hyperbranched bispyridylamine ligands as catalyst precursors for ethylene oligomerization

A series of nickel complexes containing bispyridylamine ligands is synthesized and characterized by UV-Vis, FTIR, 1H NMR, ESI-MS, and elemental analysis. All nickel complexes activated with methylaluminoxane exhibited moderate activity for ethylene oligomerization (5.30 × 104 to 2.54 × 105 g/(mol·Ni·h)), producing oligomers in the range C4–C18. The effects of reaction temperature, reaction pressure, Al/Ni molar ratio, and solvent type on the catalytic activity and product selectivity are also investigated. The resulting products are mainly low-carbon olefins (C4 and C6). Under the optimized conditions, the complex with R1 = C4H9 formed by the reaction of the corresponding ligand R1 = C4H9 with NiCl2·6H2O showed a higher catalytic activity of 2.54 × 105 g/(mol·Ni·h) compared to the complex with R2 = C6H13 and R3 = C6H11 using toluene as the solvent. Moreover, the selectivity for the C4 and C6 oligomers can reach up to 82%.

The effect of phenolic compounds on salicylaldimine nickel-catalyzed ethylene oligomerization

A salen nickel complex has been prepared in good yield with ethylenediamine, salicylaldehyde, and NiCl2·6H2O as raw materials. The structure of the complex was characterized by FTIR, 1H NMR, UV, and ESI-MS. Upon activation with methylaluminoxane (MAO), the precatalyst showed high activity for ethylene oligomerization. To reduce the simultaneous production of insoluble polymers during the nickel-catalyzed ethylene oligomerization, a series of phenolic compounds were introduced as modifiers for the production of linear α-olefins. The researched result showed that the phenolic compounds have a significant impact on the selectivity of oligomers and the concentration of polymers. With the increase of phenolic compounds, the content of polymers decreased and the distribution of oligomers gradually shifted toward lighter olefins. The sterically hindered 4-tert-butyphenol proved to be an especially efficient polymer-retarding modifier among the studied phenolic compounds in this work. Furthermore, the retarding effect of phenolic compounds toward insoluble polymers may be mainly related to their interaction with MAO, giving rise to larger MAO aggregates.

A Series of Novel Dendritic Salicylaldimine Iron Catalysts: Synthesis, Characterization, and Application in Ethylene Oligomerization

A series of novel dendritic salicylaldimine ligands and their corresponding iron complexes have been synthesized using 1.0 generation (1.0 G) dendritic macromolecules, salicylaldehyde and FeCl2 · 4H2O as raw materials. The structures of the ligands and iron complexes were characterized by FT-IR, 1H NMR, UV, ESI-MS, and elemental analysis. The dendritic salicylaldimine iron complexes presented moderate catalytic activity in ethylene oligomerization and selectivity for higher carbon number olefins products (≥C8) when they were activated with methylaluminoxane (MAO). The catalytic activity and product selectivity were related to the co-catalyst, solvent, bridged group length and reaction parameters such as reaction temperature, Al/Fe molar ratio and ethylene pressure. The complex C3 showed the highest catalytic activity (up to 13.75 × 104 g (mol Fe h)–1) and the selectivity of higher carbon number olefins (35.31%) at the optimized conditions. Moreover, the catalytic properties of dendritic salicylaldimine iron complex C3 was better than non-dendritic iron complex.

Selective Ethylene Oligomerization with Chromium-Based Metal–Organic Framework MIL-100 Evacuated under Different Temperatures

MIL-100(Cr) was synthesized and evacuated under different temperatures to generate a series of heterogeneous catalysts for ethylene oligomerization. These catalysts showed moderate catalytic activities for ethylene oligomerization but high selectivities to low carbon olefins C6, C8, and C10. Moreover, the oligomer distribution was different depending on the evacuation temperature. The XPS results showed the reduction of some CrIII active sites in the MIL-100(Cr) structure to CrII active sites, which made the catalysts show polymerization activities. The MIL-100(Cr)-250 catalyst evacuated at 250 °C exhibited the highest oligomerization and polymerization activities up to 9.27 × 105 g/(molCr·h) and 0.99 × 105 g/(molCr·h) respectively. The oligomerization selectivity to low carbon olefins C6, C8, and C10 was about 99%. The byproduct polymer from MIL-100(Cr)-250 belonged to linear polyethylene with ultrahigh molecular weight and broad molecular weight distributions. This work demonstrated that MOFs containing...

Synthesis and reactivity in ethylene oligomerization by heteroscorpionate dibromonickel(II) complexes

Novel heteroscorpionate ligands were synthesized by a Peterson rearrangement during the reaction of 2-pyridinecarboxaldehyde (or 2-quinolinecarboxaldehyde) and 1,1-carbonyl-bis(pyrazoles). Nickel(II) dibromide reacts with these ligands in THF to give the heteroscorpionate dibromo complexes of general formula LNiBr2. Crystal structures of two full-sandwich heteroscorpionate Ni(II) complexes were determined. Preliminary studies of catalytic activity in ethylene oligomerization using different organoaluminum cocatalysts were performed. The addition of one equivalent of triphenylphosphine resulted in increased catalytic activity for most examples. The catalyst system of (2-[bis(3,5-dimethylpyrazol-1-yl)methyl]pyridine nickel(II) dibromide/Et2AlCl/PPh3 dimerized ethylene with an activity of 650g oligomer mol−1Nih−1 while the share of 1-butene in the mixture has reached 75%. Tris(3,5-dimethylpyrazol-1-yl)methyl nickel(II) dibromide, activated by Et2AlCl/PPh3 produced isobutylene (75% of the butene fraction).

Chromium(II) Pincer Complexes with Dearomatized PNP and PNC Ligands: A Comparative Study of Their Catalytic Ethylene Oligomerization Activity

Monodeprotonation of the 2,6-bis(di-tert-butylphosphinomethyl) pyridine (tBuPNtBuP) at the α-lutidinyl-CH2 position with 1 equiv of KCH2C6H5 and concomitant dearomatization of the heterocycle afforded K(tBuP*NatBuP) (tBuP*= di-tert-butyl vinylic P donor, tBuP = PtBu2, Na = anionic amido N donor); its transmetalation with [CrCl2(THF)2] afforded the CrII complex [Cr(tBuP*NatBuP)Cl] (A). The X-ray diffraction analysis of A established a slightly distorted square-planar coordination geometry at the metal center and confirmed retention of the dearomatized coordinated ligand. The catalytic activity of A in ethylene oligomerization was studied and compared with that of the related CrII complexes [Cr(tBuP*NaCNHC)Cl] (B) and [Cr{Cr(tBuP*NatBuP*)Cl}2] (C) previously reported [Chem. Commun., 2015, 51, 10699 and Dalton Trans., 2016, 45, 2800, respectively].

Iron (II) complexes with hyperbranched salicylaldimine ligands: Synthesis, characterization and ethylene oligomerization

A series of novel hyperbranched salicylaldimine iron (II) complexes have been synthesized and characterized with IR, UV, MS and TG. These iron coordinative complexes, activated with methylaluminoxane (MAO), exhibited moderate activities in ethylene oligomerization (TOF=2.62–9.19×104g/molFe·h), giving higher selectivity (7.37–24.44%) for higher carbon number olefins (C10+). As reaction temperature increased, the catalytic activities firstly increased and then decreased, but the product distributions were almost independent on the temperature. With the increase of the Al/Fe molar ratio and the ethylene pressure, the catalytic activity increased rapidly and the selectivity of higher carbon number olefins increased at first and then decreased. In addition, the nature of solvent and co-catalyst, as well as the structure of catalyst significantly affected both the catalytic activities and product compositions of the resultant catalysts. Under optimized conditions ([Fe]=7μmol, 25°C, Al/Fe=500, 0.5MPa ethylene), pre-catalyst Fe1 led to catalytic activity of 6.91×104g/molFe·h and 20.48% selectivity for higher carbon number olefins.